A massively multiplayer online (MMO) role-playing game is an online computer game in which a large number of players interact with one another in a virtual world. As in most role-playing games, players assume the role of a fictional character (i.e., a Player Character) and take control over most of that character's actions. MMO games are distinguished from single-player or small multi-player games by the game's persistent world, usually hosted by a game provider, which continues to exist and evolve even when the player is away from the game.
The Player Character typically spends most of its time improving itself through the collection of experience points, which are earned, for example, through killing monsters and completing adventures assigned to the Player Character by server-controlled Non-Player Characters or Creatures (NPCs) scattered throughout the virtual world in strategic locations.
Additionally, the Player Character may improve itself by collecting items to be used for powering-up and enhancing particular skills or attachments. For example, the Player Character may combine multiple commonplace items to create a single more valuable item or attachment.